/**
  * Author: Mei
  * Date: 2020-12-05 12:01
  * Description: 函数对象的使用
  * function可以和普通函数、lambda表达式、类的成员函数(有两种方式)、类的成员变量、类的仿函数一起使用
  */
#include <vector>
#include <queue>
#include <memory>
#include <thread>
#include <mutex>
#include <condition_variable>
#include <future>
#include <functional>
#include <stdexcept>
#include <iostream>

struct Foo {
    Foo(int num) : num_(num) {}

    void print_add(int i) const { std::cout << num_ + i << '\n'; }

    int num_;
};

void print_num(int i) {
    std::cout << i << '\n';
}


struct PrintNum {
    void operator()(int i) const {
        std::cout << i << '\n';
    }
};
class A {
public:
    void display() {
        Foo foo(2);
        std::function<void(int)> f_add_display2 = std::bind(&Foo::print_add, foo, std::placeholders::_1);
        f_add_display2(2);
    }

};
int main() {
    A a;

    Foo f = 200; //转换构造函数
    f.print_add(123);

    // store a free function
    std::function<void(int)> f_display = print_num;
    f_display(-9);

    // store a lambda
    std::function<void(int)> f_display_42 = [](int i) { print_num(i); };
    f_display_42(1234);

    // store the result of a call to std::bind
    std::function<void()> f_display_31337 = std::bind(print_num, 31337);
    f_display_31337();

    // store a call to a member function
    std::function<void(const Foo &, int)> f_add_display = &Foo::print_add;
    const Foo foo(314159);
    f_add_display(foo, 1);
    f_add_display(314122, 5);

    // store a call to a data member accessor
    std::function<int(Foo const &)> f_num = &Foo::num_;
    std::cout << "num_: " << f_num(foo) << '\n';

    // store a call to a member function and object
    using std::placeholders::_1;
    std::function<void(int)> f_add_display2 = std::bind(&Foo::print_add, foo, _1);
    f_add_display2(2);

    // store a call to a member function and object ptr
    std::function<void(int)> f_add_display3 = std::bind(&Foo::print_add, &foo, _1);
    f_add_display3(3);

    // store a call to a function object
    std::function<void(int)> f_display_obj = PrintNum();
    f_display_obj(18);

}
